Sample processing device compression systems and methods

ABSTRACT

Sample processing systems and methods of using those systems for processing sample materials located in sample processing devices are disclosed. The sample processing systems include a rotating base plate on which the sample processing devices are located during operation of the systems. The systems also include a cover and compression structure designed to force a sample processing device towards the base plate. The preferred result is that the sample processing device is forced into contact with a thermal structure on the base plate. The systems and methods of the present invention may include one or more of the following features to enhance thermal coupling between the thermal structure and the sample processing device: a shaped transfer surface, magnetic compression structure, and floating or resiliently mounted thermal structure. The methods may preferably involve deformation of a portion of a sample processing device to conform to a shaped transfer surface.

The present invention relates to systems and methods for using rotatingsample processing devices to, e.g., amplify genetic materials, etc.

Many different chemical, biochemical, and other reactions are sensitiveto temperature variations. Examples of thermal processes in the area ofgenetic amplification include, but are not limited to, Polymerase ChainReaction (PCR), Sanger sequencing, etc. One approach to reducing thetime and cost of thermally processing multiple samples is to use adevice including multiple chambers in which different portions of onesample or different samples can be processed simultaneously. Examples ofsome reactions that may require accurate chamber-to-chamber temperaturecontrol, comparable temperature transition rates, and/or rapidtransitions between temperatures include, e.g., the manipulation ofnucleic acid samples to assist in the deciphering of the genetic code.Nucleic acid manipulation techniques include amplification methods suchas polymerase chain reaction (PCR); target polynucleotide amplificationmethods such as self-sustained sequence replication (3SR) andstrand-displacement amplification (SDA); methods based on amplificationof a signal attached to the target polynucleotide, such as “branchedchain” DNA amplification; methods based on amplification of probe DNA,such as ligase chain reaction (LCR) and QB replicase amplification(QBR); transcription-based methods, such as ligation activatedtranscription (LAT) and nucleic acid sequence-based amplification(NASBA); and various other amplification methods, such as repair chainreaction (RCR) and cycling probe reaction (CPR). Other examples ofnucleic acid manipulation techniques include, e.g., Sanger sequencing,ligand-binding assays, etc.

Some systems used to process rotating sample processing devices may bedescribed in U.S. Patent Application Publication No. US 2003/0124506titled MODULAR SYSTEMS AND METHODS FOR USING SAMPLE PROCESSING DEVICESand U.S. Pat. No. 6,734,401 titled ENHANCED SAMPLE PROCESSING DEVICESSYSTEMS AND METHODS (Bedingham et al.)

SUMMARY OF THE INVENTION

The present invention provides sample processing systems and methods ofusing those systems for processing sample materials located in sampleprocessing devices that are separate from the system. The sampleprocessing systems include a rotating base plate on which the sampleprocessing devices are located during operation of the systems. Thesystems also include a cover and compression structure designed to forcea sample processing device towards the base plate. The preferred resultis that the sample processing device is forced into contact with athermal structure on the base plate.

The systems and methods of the present invention may include one or moreof the following features to enhance thermal coupling between thethermal structure and the sample processing device: a shaped transfersurface, magnetic compression structure, and floating or resilientlymounted thermal structure.

In embodiments that include a shaped thermal structure, the thermalstructure may preferably be provided with a transfer surface in the formof an annular ring. It may be preferred that the transfer surface have aconvex curvature, e.g., similar to the top section of a toroidal body.By providing a shaped transfer surface in connection with a cover andcompression structure, thermal coupling efficiency between the thermalstructure and the sample processing device may be improved. It may bepreferred that the cover include compression rings that force the sampleprocessing device to conform to the shaped transfer surface of thethermal structure.

In embodiments that include magnetic compression structure, the coverand base plate may preferably include magnetic elements that, throughmagnetic attraction, draw the cover towards the base plate. When asample processing device is located between the cover and the baseplate, the compression may improve thermal coupling between the sampleprocessing device and the thermal structure. The magnets may preferablybe permanent magnets. One potential advantage of a magnetic compressionsystem is that the compressive forces may be obtained in an apparatuswith relatively low mass—which may be useful in rotating systems.

In embodiments that include a floating or biased thermal structure, thethermal structure may preferably be resiliently biased towards the coversuch that force directed downward on the thermal structure (from, e.g.,the cover) may move the thermal structure relative to the remainder ofthe base plate (which may preferably remain stationary). It may bepreferred that the thermal structure be attached to the base plateusing, e.g., one or more springs to provide the resilient bias andstructurally couple the thermal structure to the base plate.

In one aspect, the present invention provides a system for processingsample processing devices, the system including a base plate operativelycoupled to a drive system, wherein the drive system rotates the baseplate about a rotation axis, wherein the rotation axis defines a z-axis;thermal structure operatively attached to the base plate, wherein thethermal structure includes a transfer surface exposed proximate a firstsurface of the base plate; a cover facing the transfer surface, whereinthe cover includes an inner compression ring and an outer compressionring; compression structure operatively attached to the cover to forcethe cover in a first direction along the z-axis towards the transfersurface, wherein the inner and outer compression rings contact and urgea sample processing device located between the cover and the transfersurface into contact with transfer surface; and an energy source adaptedto deliver thermal energy to the thermal structure while the base plateis rotating about the rotation axis.

In another aspect, the present invention provides a system forprocessing sample processing devices, the system including a base plateoperatively coupled to a drive system, wherein the drive system rotatesthe base plate about a rotation axis, wherein the rotation axis definesa z-axis; thermal structure operatively attached to the base plate,wherein the thermal structure includes a transfer surface exposedproximate a first surface of the base plate; a cover facing the transfersurface; one or more magnetic elements operatively attached to the coverand base plate, wherein magnetic attraction between the one or moremagnetic elements attached to the cover and the base plate draw thecover in a first direction along the z-axis towards the first surface ofthe base plate such that a sample processing device located between thecover and the base plate is urged into contact with the thermalstructure of the base plate; and an energy source adapted to deliverthermal energy to the thermal structure while the base plate is rotatingabout the rotation axis.

In another aspect, the present invention provides a system forprocessing sample processing devices, the system including a base plateoperatively coupled to a drive system, wherein the drive system rotatesthe base plate about a rotation axis; a cover facing a first surface ofthe base plate; compression structure operatively attached to the coverto force the cover towards the base plate; thermal structure operativelyattached to the base plate; one or more resilient members operativelycoupled to one or both of the cover and thermal structure, wherein theone or more resilient members provide a biasing force opposing the forceof the compression structure forcing the cover towards the base plate,wherein a portion of a sample processing device located between thecover and the first surface of the base plate is urged into contact withthe thermal structure; and an energy source adapted to deliver thermalenergy to the thermal structure while the base plate is rotating aboutthe rotation axis.

In another aspect, the present invention provides a method of processingsample material located within a sample processing device by locating asample processing device between a base plate and a cover, wherein thesample processing device includes one or more process chambers locatedwithin an annular processing ring, and wherein a convex transfer surfaceis attached to the base plate, wherein the convex transfer surface is inthe form of an annular ring that is in contact with the annularprocessing ring on the sample processing device; deforming the annularprocessing ring of the sample processing device on the convex transfersurface by forcing the cover and the base plate towards each other; androtating the base plate, cover and sample processing device about anaxis of rotation while deforming the annular processing ring on theconvex transfer surface.

These and other features and advantages of the devices, systems andmethods of the invention are described below with respect toillustrative embodiments of the invention.

BRIEF DESCRIPTIONS OF THE FIGURES

FIG. 1 is an exploded perspective view of one exemplary system accordingto the present invention depicting a base plate and cover with a sampleprocessing device located therebetween.

FIG. 2 is a plan view of an alternative arrangement of magnetic elementson a base plate according to the present invention.

FIG. 3 is a perspective cross-sectional view of a portion of one baseplate with a resiliently biased thermal structure according to thepresent invention.

FIG. 4 is a perspective view of one exemplary biasing member that may beused in connection with the present invention.

FIG. 5 is an enlarged cross-sectional view of a cover forcing a sampleprocessing device to conform to a shaped transfer surface on a thermalstructure according to the present invention.

FIG. 6 is a diagram depicting the radial cross-sectional profile of oneexemplary shaped thermal transfer surface that may be used in connectionwith the present invention.

FIG. 7 is a diagram depicting the radial cross-sectional profile ofanother exemplary shaped thermal transfer surface that may be used inconnection with the present invention.

FIGS. 8A-8C depict alternative edge structures for compression rings ona cover according to the present invention.

FIG. 9 is a cross-sectional view of a portion of a sample processingdevice that may be used in connection with the present invention.

FIG. 10 is an enlarged plan view of a portion of the sample processingdevice of FIG. 9.

DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

In the following detailed description of exemplary embodiments of theinvention, reference is made to the accompanying figures of the drawingwhich form a part hereof, and in which are shown, by way ofillustration, specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand structural changes may be made without departing from the scope ofthe present invention.

The present invention provides methods and systems for sample processingdevices that can be used in methods that involve thermal processing,e.g., sensitive chemical processes such as PCR amplification, ligasechain reaction (LCR), self-sustaining sequence replication, enzymekinetic studies, homogeneous ligand binding assays, and more complexbiochemical or other processes that require precise thermal controland/or rapid thermal variations. The sample processing systems arecapable of providing simultaneous rotation of the sample processingdevice in addition to control over the temperature of sample materialsin process chambers on the devices.

Some examples of suitable sample processing devices that may be used inconnection with the methods and systems of the present invention may bedescribed in, e.g., commonly-assigned U.S. Pat. No. 6,734,401 titledENHANCED SAMPLE PROCESSING DEVICES SYSTEMS AND METHODS (Bedingham etal.) and U.S. Patent Application Publication No. US 2002/0064885 titledSAMPLE PROCESSING DEVICES. Other useable device constructions may befound in, e.g., U.S. Provisional Patent Application Ser. No. 60/214,508filed on Jun. 28, 2000 and entitled THERMAL PROCESSING DEVICES ANDMETHODS; U.S. Provisional Patent Application Ser. No. 60/214,642 filedon Jun. 28, 2000 and entitled SAMPLE PROCESSING DEVICES, SYSTEMS ANDMETHODS; U.S. Provisional Patent Application Ser. No. 60/237,072 filedon Oct. 2, 2000 and entitled SAMPLE PROCESSING DEVICES, SYSTEMS ANDMETHODS; U.S. Provisional Patent Application Ser. No. 60/260,063 filedon Jan. 6, 2001 and titled SAMPLE PROCESSING DEVICES, SYSTEMS ANDMETHODS; U.S. Provisional Patent Application Ser. No. 60/284,637 filedon Apr. 18, 2001 and titled ENHANCED SAMPLE PROCESSING DEVICES, SYSTEMSAND METHODS; and U.S. Patent Application Publication No. US 2002/0048533titled SAMPLE PROCESSING DEVICES AND CARRIERS. Other potential deviceconstructions may be found in, e.g., U.S. Pat. No. 6,627,159 titledCENTRIFUGAL FILLING OF SAMPLE PROCESSING DEVICES (Bedingham et al.)

The sample processing systems of the present invention preferablyinclude base plates attached to a drive system in manner that providesfor rotation of the base plate about an axis of rotation. When a sampleprocessing device is secured to the base plate, the sample processingdevice is rotated with the base plate. The base plates include at leastone thermal structure that can be used to heat portions of the sampleprocessing devices and may include a variety of other components aswell, e.g., temperature sensors, resistance heaters, thermoelectricmodules, light sources, light detectors, transmitters, receivers, etc.

Although relative positional terms such as “top”, “bottom”, “above”,“below”, etc. may be used in connection with the present invention, itshould be understood that those terms are used in their relative senseonly. For example, when used in connection with the devices of thepresent invention, “top” and “bottom” may be used to signify opposingsides of the base plates, with the top surface typically located closestto the sample processing device mounted to the base plate during sampleprocessing.

In actual use, elements described as “top” or “bottom” may be found inany orientation or location and should not be considered as limiting themethods, systems, and devices to any particular orientation or location.For example, the top surface of the sample processing device mayactually be located below the bottom surface of the sample processingdevice during processing (although the top surface would still be foundon the opposite side of the sample processing device from the bottomsurface).

One illustrative sample processing system is schematically depicted inthe exploded perspective view of FIG. 1. The system includes a baseplate 10 that rotates about an axis of rotation 11. The base plate 10may preferably be attached to a drive system 20 through a shaft 22. Itwill, however, be understood that the base plate 10 may be coupled tothe drive system 20 through any suitable alternative arrangement, e.g.,belts or a drive wheel operating directly on the base plate 10, etc.

Also depicted in FIG. 1 is a sample processing device 50 and cover 60that may preferably be used in connection with the base plate 10 as willbe described herein. Systems of the present invention may not actuallyinclude a sample processing device as, in most instances, sampleprocessing devices are consumable devices that are used to perform avariety of tests, etc. and then discarded. As a result, the systems ofthe present invention may be used with a variety of different sampleprocessing devices.

The depicted base plate 10 includes a thermal structure 30 thatpreferably includes a transfer surface 32 exposed on the top surface 12of the base plate 10. By “exposed” it is meant that the transfer surface32 of the thermal structure 30 can be placed in physical contact with aportion of a sample processing device 50 such that the thermal structure30 and the sample processing device are thermally coupled to transferthermal energy through conduction. It may be preferred that the transfersurface 32 of the thermal structure 30 be located directly beneathselected portions of a sample processing device 50 during sampleprocessing. The selected portions of the sample processing device 50 maypreferably include process chambers 52 as discussed in, e.g., U.S. Pat.No. 6,734,401 titled ENHANCED SAMPLE PROCESSING DEVICES SYSTEMS ANDMETHODS (Bedingham et al.).

As discussed herein, the systems of the present invention may preferablyinclude a cover 60 that, together with the base plate 10, compress asample processing device located therebetween to preferably enhancethermal coupling between the thermal structure 30 on the base plate andthe sample processing device 50. It may be preferred that both thesample processing device 50 and the cover 60 rotate with the base plate10 as it is rotated about axis 11 by drive system 20.

The compressive forces developed between the base plate 10 and the cover60 may be accomplished using a variety of different structures. Oneexemplary compression structure depicted in the embodiment of FIG. 1 aremagnetic elements 70 located on the cover 60 and corresponding magneticelements 72 located on the base plate 10. Magnetic attraction betweenthe magnetic elements 70 and 72 may be used to draw the cover 60 and thebase plate 10 towards each other, thereby compressing or deforming asample processing device 50 located therebetween.

As used herein, a “magnetic element” is a structure or article thatexhibits magnetic fields. The magnetic fields are preferably ofsufficient strength to develop the desired compressive force thatresults in thermal coupling between a sample processing device 50 andthe thermal structure 30 of base plate 10 as discussed herein. Themagnetic elements may preferably include magnetic materials, i.e.,materials that either exhibit a permanent magnetic field or that arecapable of exhibiting a temporary magnetic field.

Some examples of potentially suitable magnetic materials include, e.g.,magnetic ferrite or “ferrite” which is a substance including mixedoxides of iron and one or more other metals, e.g., nanocrystallinecobalt ferrite. However, other ferrite materials may be used. Othermagnetic materials which may be utilized in the construction of thedevice 50 may include, but are not limited to, ceramic and flexiblemagnetic materials made from strontium ferrous oxide which may becombined with a polymeric substance (such as, e.g., plastic, rubber,etc.); NdFeB (this magnetic material may also include Dysprosium);neodymium boride; SmCo (samarium cobalt); and combinations of aluminum,nickel, cobalt, copper, iron, titanium, etc.; as well as othermaterials. Magnetic materials may also include, e.g., stainless steel orother magnetizable materials that may be rendered sufficiently magneticby subjecting the magnetizable material to a sufficient electric and/ormagnetic field.

It may be preferred that the magnetic elements 70 and 72 be discretearticles operably attached to the cover 60 and base plate 10 as depictedin the embodiment of FIG. 1 (in which the magnetic elements 70 and 72are disc-shaped articles). In one alternative, however, the base plate10, thermal structure 30, and/or cover 60 may contain sufficientmagnetic material (e.g., molded or otherwise provided in the structureof the component) that separate, discrete magnetic elements are notrequired.

FIG. 2 is a view of one alternative arrangement of magnetic elements 172on an alternative base plate 110 that may preferably rotate about axis111. As depicted in FIG. 2, the magnetic elements 172 may be smallerthan those in the system depicted in FIG. 1. A potential advantage ofsuch an arrangement may be found in a more uniform distribution of themagnetic force about the circumference of the base plate 110 (especiallywhere the cover includes a complementary arrangement of magneticelements).

In another alternative, the cover 60 and/or base plate 10 may includeone or more magnetic elements in the form of electromagnets that can beactivated as needed to provide the compressive force in place of passivemagnetic elements. In such an embodiment, electric power would need tobe provided to the electromagnets during rotation of the sampleprocessing device 50.

Although not explicitly depicted in FIG. 1 the base plate 10 maypreferably be constructed such that the thermal structure 30 is exposedon both the top and the bottom surfaces 12 and 14 of the base plate 10.By exposing the thermal structure 30 on the top surface 12 of the baseplate 10, a more direct thermal path can be provided between thetransfer surface 32 of the thermal structure 30 and a sample processingdevice 50 located between the cover 60 and the base plate 10.

The thermal structure 30 is also preferably exposed on the bottomsurface 14 of the base plate 10. Exposing the thermal structure 30 onthe bottom surface 14 of the base plate 10 may provide an advantage whenthe thermal structure 30 is to be heated by electromagnetic energyemitted by a source directing electromagnetic energy onto the bottomsurface 14 of the base plate 10.

Although the system of FIG. 1 includes an electromagnetic energy sourceto deliver thermal energy to the thermal structure, the temperature ofthe thermal structure may be controlled by any suitable energy sourcethat can deliver thermal energy to the thermal structure. Examples ofpotentially suitable energy sources for use in connection with thepresent invention other than electromagnetic energy sources may include,e.g., Peltier elements, electrical resistance heaters, etc.

As used in connection with the present invention, the term“electromagnetic energy” (and variations thereof) means electromagneticenergy (regardless of the wavelength/frequency) capable of beingdelivered from a source to a desired location or material in the absenceof physical contact. Nonlimiting examples of electromagnetic energyinclude laser energy, radio-frequency (RF), microwave radiation, lightenergy (including the ultraviolet through infrared spectrum), etc. Itmay be preferred that electromagnetic energy be limited to energyfalling within the spectrum of ultraviolet to infrared radiation(including the visible spectrum).

One example of an electromagnetic energy source 90 is depicted in FIG.1, with the electromagnetic energy emitted by the source 90 directedonto the bottom surface 14 of the base plate 10 and the portion of thethermal structure 30 exposed on the bottom surface 14 of the base plate10. Examples of some suitable electromagnetic energy sources mayinclude, but are not limited to, lasers, broadband electromagneticenergy sources (e.g., white light), etc.

Where the thermal structure 30 is to be heated by a remote energysource, i.e., an energy source that does not deliver thermal energy tothe thermal structure by direct contact, the thermal structure 30 maypreferably be constructed to absorb electromagnetic energy and convertthe absorbed electromagnetic energy into thermal energy. The materialsused in the thermal structure 30 preferably possess sufficient thermalconductivity and absorb electromagnetic energy generated by theelectromagnetic source 90 at sufficient rates. In addition, it may alsobe desirable that the material or materials used for the thermalstructures 30 have sufficient heat capacity to provide a heatcapacitance effect. Examples of some suitable materials include, but arenot limited to: aluminum, copper, gold, etc. If the thermal structure 30is constructed of materials that do not, themselves, absorbelectromagnetic energy at a sufficient rate, it may be preferred thatthe thermal structure 30 include a material that improves energyabsorption. For example, the thermal structure 30 may be coated with anelectromagnetic energy absorptive material such as carbon black,polypyrrole, inks, etc.

In addition to selection of suitable materials for the thermal structure30, it may also be preferred to include grooves or other surfacestructure facing the electromagnetic energy source 90 to increase theamount of surface area exposed to the electromagnetic energy emitted bythe source 90. Increasing the surface area of the thermal structure 30exposed to the electromagnetic energy from source 90 may enhance therate at which energy is absorbed by the thermal structure 30. Theincreased surface area used in the thermal structures 30 may alsoincrease the efficiency of electromagnetic energy absorption.

It may further be desirable that the thermal structure 30 be relativelythermally isolated from the remainder of the base plate 10 such thatonly limited amounts (if any) of the thermal energy in the thermalstructure 30 is transferred to the remainder of the base plate 10. Thatthermal isolation may be achieved, for example, by manufacturing thesupport structure of the base plate 10 of materials that absorb onlylimited amounts of thermal energy, e.g. polymers, etc. Some suitablematerials for the support structure of base plate 10 include, e.g.,glass-filled plastics (e.g., polyetheresterketone), silicones, ceramics,etc.

Although the base plate 10 includes a thermal structure 30 in the formof a substantially continuous circular ring, the thermal structures usedin base plates of systems according to the present invention mayalternatively be provided as a series of discontinuous thermal elements,e.g., circles, squares, located beneath process chambers on the sampleprocessing device 50. One potential advantage, however, of a continuousring thermal structure 30 is that temperature of the thermal structure30 may equilibrate during heating. If a group of process chambers in asample processing device are arranged such that they are in directcontact with the transfer surface 32 of the thermal structure 30, thereis a potential to improve chamber-to-chamber temperature uniformity forall process chambers located above the continuous thermal structure 30.

Although the depicted base plate 10 includes only one thermal structure30, it will be understood that base plates in the systems of the presentinvention could include any number of thermal structures that arenecessary to transfer thermal energy to or from the selected processchambers in a sample processing device located thereon. Further, it maybe preferred that, where more than one thermal structure is provided,the different thermal structures be independent of each other such thatno significant amount of thermal energy is transferred between thedifferent independent thermal structures. One example of an alternativein which independent thermal structures are provided may be in the formof concentric annular rings.

FIG. 3 is a perspective cross-sectional view of a portion of the baseplate 10 and thermal structure 30 of the system depicted in FIG. 1 takenalong line 3-3 in FIG. 1. The base plate 10 includes main body 16 towhich the thermal structure 30 is attached. Although not seen in FIG. 3,the main body 16 may preferably be fixedly attached to a spindle used torotate the base plate 10. By fixedly attached, it is meant that the mainbody 16 preferably does not move relative to the spindle when a sampleprocessing device is compressed between the cover 60 and the base plate10 during operation of the system.

As depicted in FIG. 3, the thermal structure 30 may preferably begenerally U-shaped below the transfer surface 32. Such shaping maypreferably accomplish a number of functions. For example, the U-shapedthermal structure 30 may increase the surface area onto whichelectromagnetic energy is incident, thus potentially increasing theamount and rate at which energy is transferred to the thermal structure30. In addition, the U-shaped thermal structure may present a lowerthermal mass for the thermal structure 30.

As discussed herein, one optional feature of systems of the presentinvention is the floating or suspended attachment of the thermalstructure 30 such that the thermal structure 30 and the cover 60 areresiliently biased towards each other. It may be preferred that thethermal structure 30 be coupled to the base plate 10 by one or moreresilient members, with the one or more resilient members providing abiasing force opposing the force applied by the compression structure(e.g., magnets). In such a system, it may be preferred that the thermalstructure 30 be capable of movement relative to the main body 16 of thebase plate 10 in response to compressive forces between the base plate10 and the cover 60. Movement of the thermal structure 30 may preferablybe limited to a z-axis direction that is preferably aligned with(preferably parallel to) the axis of rotation.

Resilient coupling of the thermal structure 30 may be advantageous byproviding improved compliance with the surface of the sample processingdevice 50. The floating attachment of the thermal structure 30 may helpto compensate for, e.g., surfaces that are not flat, variations inthickness, etc. Resilient coupling of the thermal structure 30 may alsoimprove uniformity in the compressive forces developed between the cover60 and the thermal structure 30 when a sample processing device 50 iscompressed between the two components.

Many different mechanisms may be used to resiliently couple the thermalstructure 30. One exemplary mechanism is depicted in FIGS. 3 and 4 inthe form of a flat spring 40 that is attached to the main body 16 andthe thermal structure 30. The depicted flat spring 40 includes an innerring 42 and spring arms 44 that extend to an outer ring 46. The innerring 42 is attached to the main body 16 and the outer ring 46 isattached to a flange 36 on the thermal structure 30. Attachment of thespring 40 may be accomplished by any suitable technique or techniques,e.g., mechanical fasteners, adhesives, solder, brazing, welding, etc.

The forces generated by the flat spring 40 may be adjusted by changingthe length of the cuts 45 defining the spring arms 44, changing theradial width of the spring arms 44, changing the thickness of the springarms 44 (in the z-axis direction), selection of materials for the spring40, etc.

It may be preferred that the force urging the base plate 10 and cover 60towards each other result in physical contact between the main body 16of the base plate 10 and the cover 60 within the circle bounded by theinner edge of the transfer surface 32 of the thermal structure 30. Inother words, the magnetic attraction force in the depicted embodimentpreferably draws the cover 60 against the main body 16 of the base plate10. As a result, the forces exerted on the portion of the sampleprocessing device 50 clamped between the cover 60 and the transfersurface 32 are exerted by the flat spring 40 (or other resilient membersif used). In other words, control over the clamping force may preferablybe controlled by the resilient member/flat spring 40.

To achieve the result described in the preceding paragraph it may bepreferred that the clamping force generated between the cover 60 and themain body 16 of the base plate 10 be greater than the biasing forceoperating to force the transfer surface 32 of the thermal structure 30towards the cover 60. As a result, the cover 60 is drawn into contactwith the main body 16 and the resilient member (e.g., flat spring 40 inthe depicted embodiment) controls the forces applied to the sampleprocessing device 50 between the cover 60 and the transfer surface.

In the depicted embodiment an insulating element 38 is located betweenthe outer ring 46 and the flange 36. The insulating element 38 may servea number of functions. For example, the insulating element 38 may reducethe transfer of thermal energy between the outer ring 46 of the spring40 and the flange 36 of the thermal structure 30. Another potentialfunction of the insulating element 38 may be to provide a pre-load tothe spring 40 such that the force with which the thermal structure 30 isbiased towards the top surface 12 of the base plate 10 is at or above aselected level. A thicker insulating element 38 would typically beexpected to increase the pre-load while a thinner insulating element 38would typically be expected to reduce the pre-load. Examples of somepotentially suitable materials for insulating element may includematerials with lower thermal conductivity than metals, e.g., polymers,ceramics, elastomers, etc.

Although a flat spring 40 is one example of a resilient member that canbe used to resiliently couple the thermal structure 30, many otherresilient members could be used in place of or in addition to thedepicted flat spring 40. Examples of some other potentially suitableresilient members may include, e.g., leaf springs, elastomeric elements,pneumatic structures (e.g., pistons, bladders, etc.), etc.

Although the flat spring 40 and the main body 16 of the base plate 10are depicted as separate components in the exemplary embodiment of FIGS.1 and 3, alternatives may be possible which the functions of the mainbody 16 and the spring 40 are accomplished in a single, unitarycomponent.

One example of other optional features of sample processing systems ofthe present invention is depicted in connection with FIG. 5 which is anenlarged cross-sectional view of a sample processing device 250 heldunder compression between a thermal structure 230 and a cover 260.

In the embodiment seen in FIG. 5, the transfer surface 232 of thethermal structure 230 may preferably be a shaped surface with a raisedportion located between an inner edge 231 and an outer edge 233 (whereinner edge 231 is closest to the axis of rotation about which thethermal structure rotates as discussed herein). The raised portion ofthe transfer surface 232 may preferably be closer to the cover 260 thanthe portions of the thermal structure at the inner and outer edges 231and 233 before the sample processing device 250 is contacted by thecover 260. The transfer surface 232 may preferably have a convexcurvature when seen in a radial cross-section as depicted in FIG. 5. Theconvex transfer surface 232 may be defined by a circular curve or anyother curved profile, e.g., elliptical, etc.

FIGS. 6 and 7 depict alternative shaped transfer surfaces that may beused in connection with thermal structures that are provided as, e.g.,annular rings. One such variation as depicted in FIG. 6 includes athermal structure 330 (depicted in cross-section to illustrate itsprofile). The thermal structure 330 includes a shaped transfer surface332 with an inner edge 331 and an outer edge 333. The inner edge 331 islocated proximate an axis of rotation about which the thermal structure330 is rotated as discussed herein. Also depicted is a plane 301 (seenon edge in FIG. 6) that is transverse to the axis of rotation.

In the depicted embodiment, the plane 301 extends through the outer edge333 of the shaped transfer surface 332. Unlike the transfer surface 232of FIG. 5 in which the inner and outer edges 231 and 233 are located onthe same plane, the inner edge 331 of the transfer surface 332 maypreferably be located at an offset (o) distance from the reference plane301 as depicted in FIG. 6. It may be preferred that the inner edge 331of the transfer surface 332 be located closer to the cover (not shown)than the outer edge 333.

As discussed herein, the shaped transfer surface 332 may preferablyinclude a raised portion between the inner edge 331 and the outer edge333. The height (h) of the raised portion is depicted in FIG. 6 relativeto the plane 301, with the height (h) preferably representing themaximum height of the raised portion of the transfer surface 332.

Although the shaped transfer surfaces 232 and 332 depicted in FIGS. 5and 6 include a raised portion with a maximum height located between theinner and outer edges of the transfer surfaces, the maximum height ofthe raised portion may alternatively be located at the inner edge of thetransfer surface. One such embodiment is depicted in FIG. 7 in which across-sectional view of a portion of a thermal structure 430 isdepicted. The thermal structure 430 includes a shaped transfer surface432 with an inner edge 431 and an outer edge 433 as discussed above. Thetransfer surface 432 preferably includes a raised portion with a height(h) above a reference plane 401 that extends through the outer edge 433of the transfer surface 432.

Unlike the transfer surfaces of FIGS. 5 and 6, however, the raisedportion of the transfer surface 432 has its maximum height (h) locatedat the inner edge 431. From the maximum height (h), the transfer surfacecurves downward in a convex curve towards the outer edge 433. In such anembodiment, the inner edge 431 is located at an offset (o) distance fromthe reference plane 401 that is equal to the height (h).

The amount by which the transfer surfaces 232, 332, 432 deviate from aplanar surface may be exaggerated in FIGS. 5-7. The height (h) may insome sense be a function of the radial distance from the inner edge tothe outer edge of the transfer surface. For transfer surfaces with aradial width of, e.g., 4 centimeters or less, preferably 2 centimetersor less, and even 1 centimeter or less, it may be preferred that theheight (h) be within a range with a lower value greater than zero,preferably 0.02 millimeters (mm) or more, more preferably 0.05millimeters or more. At the upper end of the range, it may be preferredthat the height (h) be 1 millimeter or less, preferably 0.5 mm or less,and even 0.25 millimeters or less.

Returning to FIG. 5, by providing a shaped transfer surface inconnection with a cover 260 and compression structure of the presentinvention, thermal coupling efficiency between the thermal structure 230and the sample processing device 250 may be improved. The shapedtransfer surface 232 in combination with the force applied by the cover260 may preferably deform the sample processing device 250 such that itconforms to the shape of the transfer surface 232. Such deformation ofthe sample processing device 250 may be useful in promoting contact evenif the surface of the sample processing device 250 facing the transfersurface 232 or the transfer surface 232 itself include irregularitiesthat could otherwise interfere with uniform contact in the absence ofdeformation.

If the sample processing device 250 includes process chambers (see,e.g., chambers 52 on sample processing device 50 in FIG. 1), it may bepreferred to provide an optical window 268 in the cover 260 that allowstransmission of electromagnetic energy through the cover 260. Suchelectromagnetic energy may be used to, e.g., monitor process chambers,interrogate process chambers, heat process chambers, excite materials inthe process chambers, etc. By optical window, it is meant that theselected portion of the cover 260 transmits electromagnetic withselected wavelengths. That transmission may be through transmissivematerials or through a void formed in the cover 260.

To further promote deformation of the sample processing device 250 toconform to the shape of the transfer surface 232, it may be preferred toinclude compression rings 262 and 264 in the cover 260, such that therings 262 and 264 contact the sample processing device 250—essentiallyspanning the portion of the sample processing device 250 facing thetransfer surface 232. It may be further preferred that substantially allcompression force transfer between the cover 260 and the thermalstructure 230 occurs through the inner and outer compression rings 262and 264 of the cover 260.

To potentially further enhance conformance of the sample processingdevice 250 to the transfer surface 232, it may be preferred that theinner and outer compression rings 262 and 264 include an edge treatment266 such that minor variations in dimensions of the different components(cover, sample processing device, thermal structure, etc.) can be atleast partially compensated for by the edge treatments 266. One exampleof suitable edge treatments may be a rounded structure that promotespoint contact between the sample processing device 250 and thecompression rings 262 and 264. Other potential examples of potentiallysuitable edge treatments may include, e.g., a resilient gasket 366 adepicted in FIG. 8A, a cantilevered member 366 b depicted in FIG. 8B,and a triangular structure 366 c as depicted in FIG. 8C.

In another variation, it should be understood that although the depictedsystems include resilient members coupling the thermal structures to thebase plates, an alternative arrangement could be used in which the innerand outer compression rings 262 and 264 are resiliently coupled to thecover 260 by one or more resilient members. Resiliently mounting thecompression rings 262 and 264 on the cover 260 may also serve to providesome compensation in the system for, e.g., surfaces that are not flat,variations in thickness, etc. Resilient coupling of the compressionrings may also improve uniformity in the compressive forces developedbetween the cover 260 and the thermal structure 230 when a sampleprocessing device 250 is compressed between the two components.

As discussed herein, it may be preferred that the portion of the sampleprocessing device 250 in contact with the transfer surface 232 (or othershaped transfer surfaces) exhibit some compliance that, undercompression, enables the sample processing device 250 to conform to theshape of the transfer surface 232. That compliance may be limited to theportions of the sample processing device located in contact with thetransfer surface 232. Some potentially suitable sample processingdevices that may include a compliant portion adapted to conform to ashaped thermal transfer surface are described in, e.g., U.S. patentapplication Ser. No. ______, titled COMPLIANT MICROFLUIDIC SAMPLEPROCESSING DISKS, filed on even date herewith (Attorney Docket No.60876US002) and U.S. patent application Ser. No. ______, titled MODULARSAMPLE PROCESSING APPARATUS AND METHODS, filed on even date herewith(Attorney Docket No. 60753US002).

As discussed in the documents identified in the preceding paragraph,compliance of sample processing devices may be enhanced if the devicesinclude annular processing rings that are formed as composite structuresincluding cores and covers attached thereto using pressure sensitiveadhesives. A portion of one such composite structure is depicted in FIG.9 which includes a device 450 having a body 480 to which covers 482 and486 are attached using adhesives (preferably pressure sensitiveadhesives) 484 and 488 (respectively). Where process chambers areprovided in a circular array (as depicted in FIGS. 1 and 3) that isformed by a composite structure such as that seen in FIG. 9, the processchambers and covers may preferably define a compliant annular processingring that is adapted to conform to the shape of an underlying thermaltransfer surface when the sample processing disk is forced against ashaped thermal transfer surface. The compliance is preferably achievedwith some deformation of the annular processing ring while maintainingthe fluidic integrity of the process chambers (i.e., without causingleaks).

The body 480 and the different covers 482 and 486 used to seal any fluidstructures (such as process chambers) in the sample processing devicesmay be manufactured of any suitable material or materials. Examples ofsuitable materials may include, e.g., polymeric materials (e.g.,polypropylene, polyester, polycarbonate, polyethylene, etc.), metals(e.g., metal foils), etc. The covers may preferably, but notnecessarily, be provided in generally flat sheet-like pieces of, e.g.,metal foil, polymeric material, multi-layer composite, etc. It may bepreferred that the materials selected for the body and the covers of thedisks exhibit good water barrier properties.

It may be preferred that at least one of the covers 482 and 486 beconstructed of a material or materials that substantially transmitelectromagnetic energy of selected wavelengths. For example, it may bepreferred that one of the covers 482 and 486 be constructed of amaterial that allows for visual or machine monitoring of fluorescence orcolor changes within the process chambers.

It may also be preferred that at least one of the covers 482 and 486include a metallic layer, e.g., a metallic foil. If provided as ametallic foil, the cover may preferably include a passivation layer onthe surface that faces the interior of the fluid structures to preventcontact between the sample materials and the metal. Such a passivationlayer may also function as a bonding structure where it can be used in,e.g., hot melt bonding of polymers. As an alternative to a separatepassivation layer, any adhesive layer used to attach the cover to thebody 480 may also serve as a passivation layer to prevent contactbetween the sample materials and any metals in the cover.

In some embodiments, one cover 482 may preferably be manufactured of apolymeric film (e.g., polypropylene) while the cover 486 on the oppositeside of the device 450 may preferably include a metallic layer (e.g., ametallic foil layer of aluminum, etc.). In such an embodiment, the cover482 preferably transmits electromagnetic radiation of selectedwavelengths, e.g., the visible spectrum, the ultraviolet spectrum, etc.into and/or out of the process chambers while the metallic layer ofcover 486 facilitates thermal energy transfer into and/or out of theprocess chambers using thermal structures/surfaces as described herein.

The covers 482 and 486 may be attached to the body 480 by any suitabletechnique or techniques, e.g., melt bonding, adhesives, combinations ofmelt bonding and adhesives, etc. If melt bonded, it may be preferredthat both the cover and the surface to which it is attached include,e.g., polypropylene or some other melt bondable material, to facilitatemelt bonding. It may, however, be preferred that the covers 482 and 486be attached using pressure sensitive adhesive. The pressure sensitiveadhesive may be provided in the form of a layer of pressure sensitiveadhesive that may preferably be provided as a continuous, unbroken layerbetween the cover and the opposing surface of the body 480. Examples ofsome potentially suitable attachment techniques, adhesives, etc. may bedescribed in, e.g., U.S. Pat. No. 6,734,401 titled ENHANCED SAMPLEPROCESSING DEVICES SYSTEMS AND METHODS (Bedingham et al.) and U.S.Patent Application Publication No. US 2002/0064885 titled SAMPLEPROCESSING DEVICES.

Pressure sensitive adhesives typically exhibit viscoelastic propertiesthat may preferably allow for some movement of the covers relative tothe underlying body to which the covers are attached. The movement maybe the result of deformation of the annular processing ring to, e.g.,conform to a shaped transfer surface as described herein. The relativemovement may also be the result of different thermal expansion ratesbetween the covers and the body. Regardless of the cause of the relativemovement between covers and bodies in the disks of the presentinvention, it may be preferred that the viscoelastic properties of thepressure sensitive adhesive allow the process chambers and other fluidfeatures of the fluid structures to preferably retain their fluidicintegrity (i.e., they do not leak) in spite of the deformation.

Sample processing devices that include annular processing rings formedas composite structures using covers attached to bodies withviscoelastic pressure sensitive adhesives may, as described herein,exhibit compliance in response to forces applied to conform the annularprocessing rings to shaped transfer surfaces. Compliance of annularprocessing rings in sample processing devices used in connection withthe present invention may alternatively be provided by, e.g., locatingthe process chambers in an (e.g., circular) array within the annularprocessing ring in which a majority of the area is occupied by voids inthe body 480. The process chambers themselves may preferably be formedby voids in the body 480 that are closed by the covers 482 and 486attached to the body 480.

FIG. 10 is a plan view of a portion of one major surface of a sampleprocessing device of the present invention. The portion of the device450 depicted in FIG. 10 includes a portion of an annular processing ringhaving an outer edge 485 and an inner edge 487. Process chambers 452 arelocated within the annular processing ring and, as discussed herein, maypreferably be formed as voids that extend through the body 480, with thecovers 482 and 486 defining the volume of the of the process chambers452 in connection with the voids. To improve compliance or flexibilityof the annular processing ring occupied by the process chambers 452, itmay be preferred that the voids of the process chambers 452 occupy 50%or more of the volume of the body 480 located within the annularprocessing ring.

It may be preferred that the inner compression ring (see reference no.262 in FIG. 6) contact the device 450 along the inner edge 487 of theannular processing ring or between the inner edge 487 and the innermostportion of the process chambers 452. It may also be preferred that theouter compression ring (see reference no. 264 in FIG. 6) contact thedevice 450 along the outer edge 485 of the annular processing ring orbetween the outer edge 485 and the outermost portion of the processchambers 452.

Compliance of the annular processing rings in sample processing devicesused in connection with the present invention may preferably be providedby a combination of an annular processing ring formed as a compositestructure using viscoelastic pressure sensitive adhesive and voidslocated within the annular processing ring. Such a combination mayprovide more compliance than either approach taken alone.

As used herein and in the appended claims, the singular forms “a,”“and,” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a” or “the”component may include one or more of the components and equivalentsthereof known to those skilled in the art.

All references and publications cited herein are expressly incorporatedherein by reference in their entirety into this disclosure. Exemplaryembodiments of this invention are discussed and reference has been madeto some possible variations within the scope of this invention. Theseand other variations and modifications in the invention will be apparentto those skilled in the art without departing from the scope of theinvention, and it should be understood that this invention is notlimited to the exemplary embodiments set forth herein. Accordingly, theinvention is to be limited only by the claims provided below andequivalents thereof.

1. A system for processing sample processing devices, the systemcomprising: a base plate operatively coupled to a drive system, whereinthe drive system rotates the base plate about a rotation axis, whereinthe rotation axis defines a z-axis; thermal structure operativelyattached to the base plate, wherein the thermal structure comprises atransfer surface exposed proximate a first surface of the base plate; acover facing the transfer surface, wherein the cover comprises an innercompression ring and an outer compression ring; compression structureoperatively attached to the cover to force the cover in a firstdirection along the z-axis towards the transfer surface, wherein theinner and outer compression rings contact and urge a sample processingdevice located between the cover and the transfer surface into contactwith transfer surface; and an energy source adapted to deliver thermalenergy to the thermal structure while the base plate is rotating aboutthe rotation axis.
 2. A system according to claim 1, wherein the exposedtransfer surface comprises a convex transfer surface in the form of anannular ring.
 3. A system according to claim 1, wherein the exposedtransfer surface is in the form of an annular ring that comprises aninner edge and an outer edge proximate the first surface of the baseplate, wherein the outer edge of the transfer surface is offset in thefirst direction along the z-axis relative to the inner edge of thetransfer surface.
 4. A system according to claim 3, wherein the exposedtransfer surface comprises a convex transfer surface.
 5. A systemaccording to claim 1, wherein the inner and outer compression ringscomprise a compliant structure in contact with a sample processingdevice, wherein the compliant structure exhibits elastic deformationwhen urging a sample processing device into contact with the transfersurface.
 6. A system according to claim 1, further comprising one ormore resilient members operatively coupled to one or both of the coverand thermal structure, wherein the one or more resilient members providea biasing force opposing the force of the compression structure forcingthe cover towards the base plate.
 7. A system according to claim 1,wherein the one or more resilient members couple the thermal structureto the base plate.
 8. A system according to claim 7, wherein the thermalstructure is movable relative to the first surface of the base platewhen a portion of a sample processing device located between the coverand the base plate is urged into contact with the transfer surface ofthe thermal structure.
 9. A system according to claim 7, wherein the oneor more resilient members comprise a flat spring.
 10. A system accordingto claim 7, wherein the base plate comprises a stop against which thethermal structure is forced in the absence of contact from the cover.11. A system according to claim 1, wherein the compression structurecomprises one or more magnetic elements operatively attached to thecover and base plate, wherein magnetic attraction between the one ormore magnetic elements attached to the cover and the base plate draw thecover towards the first surface of the base plate.
 12. A systemaccording to claim 11, wherein the one or more magnetic elementscomprise permanent magnets.
 13. A system according to claim 11, whereinthe one or more magnetic elements comprise a first set of permanentmagnets operatively attached to the cover and a second set of permanentmagnets operatively attached to the base plate.
 14. A system accordingto claim 1, wherein the compression structure comprises mechanicalclamps operatively attached to the cover and the base plate.
 15. Asystem according to claim 1, wherein the energy source comprises anelectromagnetic energy source adapted to direct electromagnetic energyonto a portion of the thermal structure while the base plate is rotatingabout the rotation axis.
 16. A system for processing sample processingdevices, the system comprising: a base plate operatively coupled to adrive system, wherein the drive system rotates the base plate about arotation axis, wherein the rotation axis defines a z-axis; thermalstructure operatively attached to the base plate, wherein the thermalstructure comprises a transfer surface exposed proximate a first surfaceof the base plate; a cover facing the transfer surface; one or moremagnetic elements operatively attached to the cover and base plate,wherein magnetic attraction between the one or more magnetic elementsattached to the cover and the base plate draw the cover in a firstdirection along the z-axis towards the first surface of the base platesuch that a sample processing device located between the cover and thebase plate is urged into contact with the thermal structure of the baseplate; and an energy source adapted to deliver thermal energy to thethermal structure while the base plate is rotating about the rotationaxis.
 17. A system according to claim 16, wherein the one or moremagnetic elements comprise permanent magnets.
 18. A system according toclaim 16, wherein the one or more magnetic elements comprise a first setof permanent magnets operatively attached to the cover and a second setof permanent magnets operatively attached to the base plate.
 19. Asystem according to claim 16, further comprising one or more resilientmembers operatively coupled to one or both of the cover and thermalstructure, wherein the one or more resilient members provide a biasingforce opposing the magnetic attraction drawing the cover towards thefirst surface of the base plate.
 20. A system according to claim 19,wherein the one or more resilient members couple the thermal structureto the base plate.
 21. A system according to claim 20, wherein thethermal structure is movable relative to the first surface of the baseplate when a portion of a sample processing device located between thecover and the base plate is urged into contact with the transfer surfaceof the thermal structure.
 22. A system according to claim 20, whereinthe one or more resilient members comprise a flat spring.
 23. A systemaccording to claim 20, wherein the base plate comprises a stop againstwhich the thermal structure is forced in the absence of contact from thecover.
 24. A system according to claim 16, wherein the exposed transfersurface comprises a convex transfer surface in the form of an annularring.
 25. A system according to claim 16, wherein the exposed transfersurface is in the form of an annular ring that comprises an inner edgeand an outer edge proximate the first surface of the base plate, whereinthe outer edge of the transfer surface is offset in the first directionalong the z-axis relative to the inner edge of the transfer surface. 26.A system according to claim 25, wherein the exposed transfer surfacecomprises a convex transfer surface.
 27. A system according to claim 16,wherein the energy source comprises an electromagnetic energy sourceadapted to direct electromagnetic energy onto a portion of the thermalstructure while the base plate is rotating about the rotation axis. 28.A system for processing sample processing devices, the systemcomprising: a base plate operatively coupled to a drive system, whereinthe drive system rotates the base plate about a rotation axis; a coverfacing a first surface of the base plate; compression structureoperatively attached to the cover to force the cover towards the baseplate; thermal structure operatively attached to the base plate; one ormore resilient members operatively coupled to one or both of the coverand thermal structure, wherein the one or more resilient members providea biasing force opposing the force of the compression structure forcingthe cover towards the base plate, wherein a portion of a sampleprocessing device located between the cover and the first surface of thebase plate is urged into contact with the thermal structure; and anenergy source adapted to deliver thermal energy to the thermal structurewhile the base plate is rotating about the rotation axis.
 29. A systemaccording to claim 28, wherein the one or more resilient members couplethe thermal structure to the base plate.
 30. A system according to claim28, wherein the thermal structure is movable relative to the firstsurface of the base plate when a portion of a sample processing devicelocated between the cover and the base plate is urged into contact withthe transfer surface of the thermal structure.
 31. A system according toclaim 29, wherein the one or more resilient members comprise a flatspring.
 32. A system according to claim 29, wherein the base platecomprises a stop against which the thermal structure is forced in theabsence of contact from the cover.
 33. A system according to claim 29,wherein the energy source comprises an electromagnetic energy sourceadapted to direct electromagnetic energy onto a portion of the thermalstructure while the base plate is rotating about the rotation axis. 34.A method of processing sample material located within a sampleprocessing device, the method comprising: locating a sample processingdevice between a base plate and a cover, wherein the sample processingdevice comprises one or more process chambers located within an annularprocessing ring, and wherein a convex transfer surface is attached tothe base plate, wherein the convex transfer surface is in the form of anannular ring that is in contact with the annular processing ring on thesample processing device; deforming the annular processing ring of thesample processing device on the convex transfer surface by forcing thecover and the base plate towards each other; and rotating the baseplate, cover and sample processing device about an axis of rotationwhile deforming the annular processing ring on the convex transfersurface.
 35. A method according to claim 34, wherein the convex transfersurface is resiliently mounted to the base plate, and wherein forcingthe cover and the base plate towards each other moves the convextransfer surface relative to the base plate.
 36. A method according toclaim 34, wherein the transfer surface comprises an inner edge and anouter edge proximate the first surface of the base plate, wherein theouter edge of the transfer surface is offset in a first direction alongthe axis of rotation relative to the inner edge of the transfer surface.37. A method according to claim 34, wherein the cover comprises an innercompression ring and an outer compression ring, and wherein the innerand outer compression rings contact and deform the sample processingdevice on the convex transfer surface.
 38. A method according to claim34, wherein forcing the cover and the base plate towards each othercomprises magnetically attracting the cover towards the base plate. 39.A method according to claim 34, wherein the transfer surface comprises aportion of a thermal structure, and wherein the method comprises heatingthe transfer surface by directing electromagnetic energy from anelectromagnetic energy source onto a portion of the thermal structurewhile the base plate is rotating about the rotation axis.